Semiconductor device and manufacturing method thereof

ABSTRACT

A self-light emitting display device with top-emission usually has no film that is capable of light shielding. Therefore, it is necessary to form a light-shielding layer additionally with, which leads the number of processes to increase. 
     In the present invention, plural films selected from a first coloring layer  161,  a second coloring layer  162,  and a third coloring layer  163  formed on an opposing substrate are laminated to form a light-shielding portion without using a light-shielding mask.

This application is a continuation of copending U.S. application Ser.No. 10/636,869, filed on Aug. 7, 2003 now U.S. Pat. No. 7,081,704.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor device that has acircuit including a thin film transistor (Hereinafter, TFI) and a methodof manufacturing the semiconductor device.

The semiconductor device indicates general devices that are able tofunction with utilizing characteristics of semiconductor, and includesall of a liquid crystal display device, a display device (an EL displaydevice) which has a self-light emitting element represented by anelectroluminescent (Hereinafter, EL) element, a semiconductor circuit,and an electronic apparatus using those as parts.

2. Description of the Related Art

Recently, attention has been paid to techniques of manufacturing a TFTwith using a thin semiconductor film (a thickness on the order ofseveral to several hundreds nm) formed on an insulating surface of asubstrate. It is expected that the TFT be widely applied to electronicdevices, and rapid development is required for a switching element fordriving a liquid crystal display device or an EL display device.

In a display device, attention is paid to an active matrix displaydevice in which, in order to obtain an image with a high quality, pixelelectrodes are arrange in a matrix shape and a switching elementconnected to each of the pixel electrodes is driven to performdisplaying. Above all, an EL display device that has a pixel using an ELelement that is a self-light emitting element is expected as a displaydevice in the next generation, instead of a liquid crystal displaydevice.

An EL element has an EL layer formed to be sandwiched between first andsecond electrodes, and electric current generated between the first andsecond electrodes to obtain emission of light for performing display ofan image. There are given advantages that the device is lighter, thinnerand more miniaturized since a backlight as used in a liquid crystaldisplay device is unnecessary, a view angle is wide, and smooth displayof an animation is obtained due to a quick response speed.

As a means for realizing a color display in an EL display device, theremay be given a means in which an EL material for emitting light of eachof red (R), green (G), blue (B) is used to form each light emittingportion, or a means in which an EL element for emitting light of asingle color such as white or blue is used and emitted light is made topass through a color filter or a color conversion layer for obtainingemission of light of each of RGB.

A color filter generally used for a display device has coloring layers601 to 603 respectively corresponding to R, G, and B and alight-shielding layer 604 as shown in FIGS. 6A to 6C, and absorbs a partof light irradiated to the coloring layers and transmits the other partof the light to extract light of R, G, and B. The light-shielding layer604 is generally formed of a film such as a metal (such as chromium)film or an organic film containing a black pigment, and may be providedright between adjacent pixels as shown in FIG. 6A or in a stripe-shapeas shown in FIG. 6B. In the case that pixels is arranged in a deltaarrangement, another means may be employed.

FIG. 6C shows a section along D-D′ in FIG. 6A or 6B. After thelight-shielding layer 604 and the coloring layers 601 to 603 are formedon a substrate 651, a planarization film 652 may be provided in order toperform planarization of the surface. In addition, it is possible to usethe planarization film 652 as a barrier layer against an impurityincluded in the coloring layers 601 to 603.

It is noted on a takeout direction of light emitted from an EL elementthat there is bottom-emission called in the case of taking out of a sideof a substrate that has a TFT formed as shown in FIG. 4A while there istop-emission called in the case of taking out of a side of an opposingsubstrate as shown in FIG. 4B

In the case of forming a color filter, a position for forming isdifferent in accordance with the takeout direction of emitted light. Inthe case of the bottom-emission, as shown in FIG. 4A, it is necessarythat coloring layers be provided near a TFT substrate 400 rather than apixel electrode 410 to form a color filter. That is, processes proceedin order of forming a TFT 402, forming a wiring 404, forming coloringlayers 406 to 408, forming the pixel electrode 410, forming an EL layer412, forming an opposing electrode 413, and sealing with an opposingsubstrate 401. In the case of the top-emission, as shown in FIG. 4B,coloring layers 459 to 461 are provided at a side of an opposingsubstrate 451 to form a color filter since the emitted light is obtainedfrom a side of an opposing electrode 458. That is, the process forforming the color filter is independent of ones for a TFT substrate 450.

When a color filter is formed at the side of the TFT substrate like thecase of the bottom-emission, there are problems that it is impossiblethat coloring layers themselves withstand a temperature of heattreatment in a later process and impurities in the coloring layersdiffuse due to heat to have a TFT contaminated. Therefore, it isnecessary to provide barrier layers 405 and 409, represented by a filmsuch as a silicon nitride film, above and below the portion in which thecoloring layers are formed. In the case of the top-emission, on theother hand, it is suitable that there is no necessary of worrying aboutthe above-mentioned problems since it is possible to form a color filterindependently of processes for the TFT substrate.

SUMMARY OF THE INVENTION

In an EL display device, dummy pixels are often provided at an outeredge of a displaying area to ensure a margin in order to avoid an edgeportion of an EL layer from covering the displaying area in forming theEL layer.

As described in Japanese Patent Application No. 2001-19651 (JapanesePatent Laid-Open 2002-304155), there is a method in which currentmonitoring pixels are provided outside a displaying area to performcorrection of variation in luminance in the displaying area. The pendingU.S. patent application Ser. No. 10/060,709 filed on Jan. 29, 2002corresponds to Japanese Patent Application No. 2001-19651. Also, thisU.S. Patent Application is published as Publication No. 2002/0125831 A1.An entire disclosure of this U.S. Patent Application is incorporatedherein by reference. In such case, there is a case in which a part ofthe above-mentioned dummy pixels are used as the current monitoringpixels.

Since no light should be emitted originally from such dummy pixels andcurrent monitoring pixels, it is necessary that a light-shielding layerbe formed to prevent light leakage from occurring. In the case of an ELelement with bottom-emission, there are many portions formed of opaquematerials such as a wiring and a gate electrode in a path of emittedlight from an EL layer 202 till recognition by eye, as shown in FIG. 2A.Therefore it is possible to reduce a mask for forming a light-shieldinglayer 204 in forming a color filter if the light-shielding layer 204 isformed with utilizing those materials.

On the other hand, in the case of top-emission, an EL element has noportion formed of opaque materials in a path of emitted light from an ELlayer 252 till recognition by eye, as shown in FIG. 2B. Since alight-shielding layer needs to be formed additionally, it is concernedto increase processes, lower yield, and the like.

The present invention has been accomplished in view of the aboveproblem. It is an object of the present invention to form alight-shielding layer with high precision without increasing the numberof masks and provide a display device that can obtain a high-definitiondisplay.

In general, visible light indicates light that has wavelengths of 400 to780 nm. A coloring layer used for a color filter transmits, of thisvisible light, only light that has a specific range of wavelengths toprovide coloring light, and coloring layers for different colorsnaturally have a characteristic of transmitting light with a differentrange of wavelengths from each other.

In other words, light with a wavelength that has a high transmissivitywith respect to a coloring layer is hardly transmitted through adifferent coloring layer at all. In the present invention, with a focuson this point, two or three coloring layers are laminated for a portionto be shielded from light to provide a layer that is able to shieldagainst all visible light, which is to be a light-shielding layer. Sinceit is unnecessary to form a light-shielding layer additionally, thereduction of the process makes it possible to realize lowering amanufacturing cost and improving yield.

Configurations of the present invention will be described below.

A semiconductor device according to the present invention has aplurality of different first to third coloring layers and alight-shielding portion, wherein the light-shielding portion includes alaminate of plural layers selected form the plurality of different firstto third coloring layers.

Another semiconductor device according to the present invention has asource signal line, a gate signal line, a TFT, a plurality of differentfirst to third coloring layers, and a light-shielding portion, whereinthe light-shielding portion is formed to overlap at least a portion inwhich the source signal line, the gate signal line, and the TFT areformed.

Further, another semiconductor device according to the present inventionhas a plurality of pixel electrodes, a plurality of different first tothird coloring layers, and a light-shielding portion including alaminate of plural layers selected form the plurality of different firstto third coloring layers, wherein the light-shielding portion is formedto overlap with a portion between any pixel electrode and an adjacentpixel electrode to the pixel electrode.

The present invention has a feature that the first coloring layer isprovided for red, the second coloring layer is provided for green, andthe third coloring layer is provided for blue.

The present invention has another feature that the plurality ofdifferent first to third coloring layers and the light-shielding portionare both formed on an opposing substrate.

The present invention has also another feature that the semiconductordevice is a display device using a self-light emitting element.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIGS. 1A and 1B are diagrams showing a laminated structure of coloringlayers in Embodiment Mode;

FIGS. 2A and 2B are diagrams exemplifying means for forminglight-shielding layers in the cases of top-emission and bottom-emission,respectively;

FIGS. 3A and 3B are graphs showing measurement result of transmissivityfor single, two-layer, and three-layer laminated structures;

FIGS. 4A and 4B are diagrams showing sectional structures of substratesof EL display devices with top-emission and bottom-emission,respectively;

FIGS. 5A and 5B are diagrams showing an appearance and a section of anEL display device with top-emission;

FIGS. 6A to 6C are diagrams showing configurations of typical coloringlayers;

FIG. 7 is a diagram showing a laminated structure of coloring layers ina light-shielding portion;

FIGS. 8A to 8C are diagrams showing processes for laminating coloringlayers to form light-shielding layers at the same time;

FIGS. 9A to 9E are diagrams showing processes for manufacturing anactive matrix EL display device;

FIGS. 10A to 10D are diagrams processes for manufacturing the activematrix EL display device; and

FIGS. 11A to 11F are diagrams showing examples of electronic apparatusesto which the present invention is applicable.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment Mode

FIGS. 1A and 1B show an embodiment mode of the present invention. Shownin FIG. 1A is a pixel portion of an EL display device, which has pixelsarranged in a matrix shape. Each of the pixels has a source signal line101, a first gate signal line 102, a second gate signal line 103, anelectric current supplying line 104, a switching TFT 105, an erasing TFT106, a driving TFT 107, a capacitor 108, and a pixel electrode 109. Thecapacitor 108 may not be provided particularly providing that it ispossible to keep voltage between a gate and a source of the driving TFT107 normally during a predetermined display period.

FIG. 1B shows a section along A-A′ in FIG. 1A. In forming TFTs on asubstrate 151, a first electrode 153 of the capacitor is formed at thesame time when active layers of the TFTs are formed and a secondelectrode 154 of the capacitor is formed at the same time when gateelectrodes of the TFTs are formed to form a capacitor through a gateinsulating film 155. In addition, wirings and pixel electrodes 157 areformed through an interlayer insulating film 156, and an insulatinglayer is formed of a suitable material for planarization such as resinand an opening is formed at a portion to be a light emitting potion toform banks 158. After that, an EL layer 159 and an opposing electrode160 are formed. Since the EL display device shown here has a type oftop-emission, it is preferable that a material with a high reflectivityis used for the pixel electrodes 157 and a material with a hightransmissivity is used for the opposing electrode 160.

On the other hand, first to third coloring layers 161 to 163 aresequentially formed on an opposing substrate 152 to be a color filter.In regions (denoted as ‘Dummy’ in FIG. 1A) from which emitted light isnot take out, such as a dummy pixel and a current monitoring pixel, twoor three of the first to third coloring layers are laminated to be alight-shielding layer. Furthermore, not shown in the figure, aprotective film may be formed on the coloring layers in order to performplanarization and prevent diffusion of impurities in the coloringlayers.

With respect to a light-shielding layer between adjacent pixels, threeof coloring layers may be laminated as shown by a dotted circles in FIG.7 although two of adjacent coloring layers are laminated in FIG. 1B.

FIG. 3A shows measurement result of transmissivity for each of two-layerlaminate films of coloring layers for red and blue, coloring layers forblue and green, and coloring layers for red and green. Thetransmissivity of the two-layer laminate film is nearly equal to aproduct of transmissivity of each coloring layer. Although the two-layerlaminate film of the coloring layers for red and blue has a largely goodlight-shielding characteristic that the transmissivity is on the orderof 7% or less with respect to all wavelengths, several tens percents oflight with certain wavelength is transmitted in the case of thetwo-layer laminate films of the coloring layers for blue and green andthe coloring layers for red and green.

Further, FIG. 3B shows measurement result of transmissivity of each ofcoloring layers for red, green, and blue and calculation result of aproduct of the transmissivities as the case of a three-layer laminatefilm. It makes transmissivity on the order of less than 4% with respectto all wavelengths to be the three-layer laminate film, and therefore itcan be said that the three-layer laminate film is enough to function asa light-shielding layer.

In the case of an EL display device and the like, a light-shieldinglayer of a two-layer laminate film has possibilities of realizing onlyinsufficient light-shielding since intensity of emitted light is large.Accordingly, it is desirable to be a light-shielding layer using athree-layer laminate film, as shown in FIG. 7, which is also applied toa transmissive liquid crystal display device and the like. On the otherhand, in the case of a reflective liquid crystal display device and thelike, intensity of light is not so large since natural light is used. Insuch case, a two-layer laminate film (a two-layer laminate film ofcoloring layers for red and blue or a two-layer laminate film ofcoloring layers for green and blue, which has a relatively goodlight-shielding characteristic, is desirable) may be used for alight-shielding layer.

There is a description given here as an example on a display device thatcorresponds to a general color display and has coloring layers for red,green, and blue. It is needless to say that a similar means can beapplied to a display device that has coloring layers for two differentcolors or more than four colors to be capable of multi-color display.

EMBODIMENTS Embodiment 1

An embodiment of the present invention will be described below withtaking as an example fabrication of an opposing substrate used for an ELdisplay device with top-emission. FIG. 8A to 8C schematically show thathow coloring layers and light-shielding layers are formed on an opposingsubstrate in accordance with the present embodiment.

First, as an opposing substrate 800, barium borosilicate glass oraluminum borosilicate glass, represented by glass such as Corning #7059glass or #1737 glass, is prepared. In addition, a translucent substratesuch as a quartz substrate and a plastic substrate may also be used.

Next, an organic photosensitive material (CRY-S778: COLOR MOSAIC made byFuji Film Olin Corp.) is applied to the opposing substrate 800, andpatterned with photolithography as shown in FIG. 8A to form a firstcoloring layer (R) 801 at a predetermined position.

Next, a different organic photosensitive material (CGY-S705C: COLORMOSAIC made by Fuji Film Olin Corp.) from the material for forming thefirst coloring layer (R) 801 is applied and patterned as shown in FIG.8B with photolithography to form a second coloring layer (G) 802 at apredetermined position.

Next, a different organic photosensitive material (CVB-S706C: COLORMOSAIC made by Fuji Film Olin Corp.) from the materials for the firstcoloring layer (R) 801 and the second coloring layer (G) 802 is appliedand patterned as shown in FIG. 8C with photolithography to form a thirdcoloring layer (G) 803 at a predetermined position.

As shown in FIG. 8C, a portion of the first coloring layer (R) 801overlaps a portion of the second coloring layer (G) 802 and a portion ofthe third coloring layer (B) 803 at light-shielding layers 1 to 4. Here,the light-shielding layer 1 has a region for light shielding againstlight emitting portions of dummy pixels and current monitoring pixels,and light-shielding layers 2 to 4 are formed in order to suppress lightleakage between adjacent pixels. In the first coloring layer (R) 801, aregion that does not overlap any of the first to fourth light-shieldinglayers is to be an opening portion R. Sirnilarly, in the second coloringlayer (G) 802, a region that does not overlap any of the first to fourthlight-shielding layers is to be an opening portion G, and in the thirdcoloring layer (B) 803, a region that does not overlap any of the firstto fourth light-shielding layers is to be an opening portion B.

Thus, when photolithography is performed three times, opening portionsand light-shielding layers can be formed without additionally forming alight-shielding layer of a metal film or the like.

If necessary, a protective film (not shown) for covering the respectivecoloring layers is formed. Since a step is produced between a portion inwhich the coloring layer is of a single layer and a portion in which theplural coloring layers overlap, the protective film may be used as aplanarization film. In this case, a film thickness of 2 μm to 3 μm isnecessary. In the case of achieving an aim of preventing contaminationdue to impurities in the coloring layers, it is preferable to use a filmwith a high blocking property against contamination.

Although an organic photosensitive material is applied and patternedinto a desired shape with photolithography to form the respectivecoloring layers 801 to 803 in the present embodiment, it is needless tosay that the manufacturing method thereof is not particularly limited tothe present embodiment.

In addition, an order of forming the coloring layers 801 to 803 is notlimited to the present embodiment.

Embodiment 2

In the present embodiment, a description will be given on an example ofmanufacturing an active matrix EL display device with top-emission.

FIG. 5A shows an appearance of an active matrix EL display device withtop-emission manufactured with applying the present invention. A pixelportion 502 is provided at the center of a substrate 500, and a sourcesignal line driving circuit 503, a first gate signal line drivingcircuit 504, and a second gate signal line driving circuit 505 areprovided on the periphery of the pixel portion 502. It is from anexternal circuit via a flexible printed circuit (FPC) 506 that it isperformed to power and input driving signals to the respective drivingcircuits.

FIG. 5B shows a section along C-C′ in FIG. 5A. As shown in FIG. 5B, thesubstrate 500 and an opposing substrate 501 are bonded and fixed alongtheir circumferences with a sealing material 553, and an EL layer formedin the pixel portion 502 is kept airtight in order avoid exposure toair. In addition, the opposing substrate 501 has a groove formed along aregion to which the sealing material is applied to provide a desiccant554, which suppresses degradation of the EL layer due to moisture.Besides, the opposing substrate 501 has a coloring layer 552 formed inaccordance with Embodiment Mode and Embodiment 1. As not shown in FIG.5B, a protective film may be formed to cover a surface of the coloringlayer in the case of concerning the EL layer and a TFT withcontamination due to impurities in the coloring layer.

With respect to connection of the FPC 506 and the substrate 500, ananisotropic conductive paste 551 containing a conductive material insideis used for fixing, and the conductive material is electricallyconnected to a terminal for input and output of signals.

Embodiment 3

In the present embodiment, a description will be given on amanufacturing method of TFT to be formed on a substrate, particularly,of an n-channel TFT and a p-channel TFT to be formed in a drivingcircuit portion and an n-channel TFT and a p-channel TFT to be formed ina pixel portion.

First, a base insulating film is formed of a laminate of insulatingfilms such as a silicon oxide film, a silicon nitride film, and asilicon oxynitride film (not shown in the figure). The base insulatingfilm may employ any of a two-layer structure, a single-layer film of theabove-mentioned insulating film and a structure of three or more layerslaminated. As a first layer of the base insulating film, a siliconoxynitride film of deposition with plasma CVD using SiH₄, NH₃, N₂O, andH₂ as reaction gas is formed to have a thickness of 10 to 200 nm(preferably, 50 to 100 nm). Then, as a second layer of the baseinsulating film, a silicon oxynitride film of deposition with plasma CVDusing SiH₄ and N₂O as reaction gas is formed and laminated on the firstlayer to have a thickness of 50 to 200 nm (preferably, 100 to 150 nm).

Next, as shown in FIG. 9A, a semiconductor film 902 is formed on thebase insulating film. After a semiconductor film with an amorphousstructure is deposited with a known means such as sputtering, LPCVD, orplasma CVD, treatment for crystallization (laser crystallization,thermal crystallization, thermal crystallization using a catalyst suchas nickel, or the like) is performed. It is preferable to irradiatelaser to promote crystallization after thermal crystallization using acatalyst such as nickel. Although a material for the semiconductor filmis not limited, silicon or silicon-germanium alloy is preferable as thematerial for forming the semiconductor film.

In the case of manufacturing a crystalline semiconductor film with lasercrystallizat )n, pulse-emission or continuous-emission laser such asexcimer laser, YAG laser, and YVO₄ laser may be used. Then, in the caseof using such laser, laser light emitted from a laser oscillator may begathered into a linear shape with an optical system to be irradiated toa semiconductor film. Although conditions for crystallization areappropriately selected, a pulse oscillation frequency and a laser energydensity are respectively set at 30 Hz and 100 to 400 mJ/cm² (typically,200 to 300 mJ/cm²) in the case of using excimer laser. In the case ofusing YAG laser, second harmonic thereof is used, and a pulseoscillation frequency and a laser energy density may be respectively setat 1 to 10 kHz and 300 to 600 mJ/cm² (typically, 350 to 500 mJ/cm²).Laser light gathered into a linear shape with a width of 100 to 1000 μm,for example, 400 μm, may be irradiated to whole the substrate with thean overlap ratio of the linear laser light of 50 to 98%.

Then, boron is doped to the crystallized semiconductor film 902 (channeldoping). After that, as shown in FIG. 9B, the semiconductor film 902 ispatterned into a desired shape to form an island-shaped semiconductorfilm 903 to have a thickness of 25 to 80 nm (preferably, 30 to 60 nm).Next, a surface of the semiconductor film 903 is cleaned with an etchantincluding hydrofluoric acid, and a gate insulating film 904 is formed tocover the semiconductor film 903. With plasma CVD or sputtering, thegate insulating film 904 is formed of an insulating film includingsilicon to have a thickness of 40 to 150 nm. In the present embodiment,a silicon oxynitride film (composition ratio: Si=32%, O=59%, N=7%, andH=2%) is formed with plasma CVD to have 115 nm. Of course, the gateinsulating film is not limited to the silicon oxynitride film, and asingle layer or a laminated structure of other insulating film includingsilicon may be used.

Next, a first conductive film with a film thickness of 20 to 100 nm anda second conductive film with a film thickness of 100 to 400 nm areformed and laminated on the gate insulating film. In the presentembodiment, a tantalum nitride film with a film thickness of 50 nm and atungsten film with a film thickness of 370 nm are sequentially formedand laminated on the gate insulating film 904.

Each of the first and second conductive films may be formed of anelement selected from Ta, W, Ti, Mo, Al, and Cu, or an alloy material ora compound containing the element as its main component, and a AgPdCualloy or a semiconductor film represented by a poly-silicon film towhich an impurity element such as phosphorus and the like is doped maybe used as the first and second conductive films. In addition there isno limitation to the two-layer structure, for example, a tungsten filmwith a film thickness of 50 nm, an aluminum-silicon alloy (Al—Si) filmwith a film thickness of 500 nm, and a titanium nitride film with a filmthickness of 30 nm may be sequentially laminated to be a three-layerstructure. In the case of using the three-layer structure, a tungstennitride film may be used instead of the tungsten film as the firstconductive film, an aluminum-titanium alloy (Al—Ti) film may be usedinstead of the aluminum-silicon alloy (Al—Si) film as the secondconductive film, and a titanium film may be used instead of the titaniumnitride film as the third conductive film. Also, a single-layerstructure may be employed.

After that, patterning is performed in accordance with procedures shownbelow to form respective gate electrodes and wirings. With ICP(Inductivity Coupled Plasma) etching, it is possible to perform etchingof the first and second conductive films into a desirable tapered shapewhen etching conditions (such as electric power applied to a coiledelectrode, electric power applied to an electrode at a substrate side,and a temperature of the electrode at the substrate side) areappropriately adjusted. As gas for etching, chlorine gas represented bygas such as Cl₂, BCl₃, SiCl₄, or CCl₄, fluorine gas represented by gassuch as CF₄, SF₆, or NF₃, or O₂ may be appropriately used. In thepresent embodiment, first and second etching is performed after forminga mask of resist.

The first etching has first conditions of using CF₄, C1 ₂, and O₂ as gasfor etching, setting gas flow rate of the gas at 25/25/10 (sccm),applying RF (13.56 MHz) of 700 W to a coiled electrode under a pressureof 1 Pa and applying RF (13.56 MHz) of 150 W to a substrate side (asample stage) to apply negative self-bias voltage actually. Under thefirst conditions, only the W film that is the second conductive film issubjected to etching to made into a tapered shape that has an endportion with an angle of 15 to 45°.

Then, the second etching is performed without removing the mask ofresist, under second conditions of using CF₄, and Cl₂ as gas foretching, setting gas flow rate of the gas at 30/30 (sccm), applying RF(13.56 MHz) of 500 W to the coiled electrode under a pressure of 1 Paand applying RF (13.56 MHz) of 20 W to the substrate side (the samplestage) to apply negative self-bias voltage actually. The TaN film thatis the first conductive film and the W film that is the secondconductive film are both subjected to etching at the same level underthe second conditions to become a first conductive film 905 a and asecond conductive film 905 b respectively as shown in FIG. 9C.

Next, first doping treatment is performed for doping an impurity elementthat gives a semiconductor film a conductivity type with self-aligningwhile the gate electrode is used as a mask is performed without removingthe mask of resist. For the first doping ion treatment, doping or ionimplantation may be employed. Phosphorus (P) or arsenic (As) is used asan impurity element for imparting n-type to form a first impurity region(n+ region) 906 as shown in FIG. 9C. In the first impurity region 906,the impurity element for imparting n-type is doped at a concentration of1×10²⁰ to 1×10²¹/cm³.

Next, third etching is performed without removing the mask of resist,under third conditions of using CF₄, and Cl₂ as gas for etching, settinggas flow rate of the gas at 30/30 (sccm), applying RF (13.56 MHz) of 500W to the coiled electrode under a pressure of 1 Pa and applying RF(13.56 MHz) of 20 W to the substrate side (the sample stage) to applynegative self-bias voltage actually.

After that, fourth etching is performed without removing the mask ofresist, under fourth conditions of using CF₄, C1 ₂, and O₂ as gas foretching, setting gas flow rate of the gas at 20/20/20 (sccm), applyingRF (13.56 MHz) of 500 W to a coiled electrode under a pressure of 1 Paand applying RF (13.56 MHz) of 20 W to a substrate side (a sample stage)to apply negative self-bias voltage actually. The third and fourthetching subjects the W film and the TaN film to anisotropic etching.Further, oxygen is included in the gas for etching to generatedifference between etching rates to the W film and the TaN film and makethe etching rates to the W film faster than the etching rate to the TaNfilm. The gate insulating film that is not covered with the firstconductive film is subjected to etching to become thin. At this stage,there are formed a gate electrode 908 that has a first conductive layer(TaN film) 908 a as a lower layer and a second conductive layer (W film)908 b as an upper layer, and an electrode (not shown in the figure).

Next, second doping treatment for doping an impurity element that givesa semiconductor film a conductivity type while the gate electrode isused as a mask is performed without removing the mask of resist. For thesecond doping treatment, ion doping or ion implantation may be employed.In the present embodiment, ion doping is used under conditions of usinggas in which phosphine (PH₃) diluted to 5% with hydrogen and setting thegas flow rate at 30 sccm, a dose volume at 1.5×10¹⁴ atoms/cm², and anacceleration voltage at 90 keV.

At this time, the mask of resist and the second conductive layer 908 bfunction as masks, and a second impurity region (n⁻ region) 907 that isnot overlapped with the gate electrode and a third impurity region (n⁻region) 909 that is overlapped with a part of the gate electrode areformed with the second doping treatment. In the second impurity region907, the impurity element for imparting n-type is doped at aconcentration of 1×10¹⁶ to 1×10¹⁷/cm³.

Next, after removing the mask of resist, a mask 910 of resist is newlyformed to perform third doping treatment as shown in FIG. 9E. With thethird doping treatment, fourth, fifth, and sixth impurity regions, towhich an impurity element such as boron for imparting a conductivitytype of p-type is doped, are formed in the semiconductor layer forforming a p-channel TFT. It is noted that what is necessary is obtaininga region that functions as a source region and a drain region and thefourth to sixth impurity regions are not indispensable.

The fourth impurity region is a region into which the impurity elementfor imparting p-type is to be doped at a concentration of 1×10²⁰ to1×10²¹/cm³. Although the fourth impurity region is also a region (n⁺region) to which phosphorus (P) is doped in the previous process, theconductivity type thereof is p-type since the concentration of the dopedimpurity element for imparting p-type is one and half to three times ashigh as that of the doped phosphorus. Here, a region that has the samerange of concentration as that of the fourth impurity region is alsocalled p⁺ region.

The fifth impurity region is a region formed in a region that is notoverlapped with a tapered portion of the first conductive layer, and theimpurity element for imparting p-type is doped at a concentration of1×10¹⁸ to 1×10²⁰/cm³ therein. Although the fifth impurity region is alsoa region (n⁻ region) to which phosphorus (P) is doped in the previousprocess, the conductivity type thereof is p-type since the concentrationof the doped impurity element for imparting p-type is one and half tothree times as high as that of the doped phosphorus. Here, a region thathas the same range of concentration as that of the fifth impurity regionis also called p⁻ region.

The sixth impurity region is an impurity region that is overlapped witha tapered portion of the first conductive layer. Although the sixthimpurity region is also a region (n⁻ region) to which phosphorus (P) isdoped in the previous process, the conductivity type thereof is p-typesince the concentration of the doped impurity element for impartingp-type is one and half to three times as high as that of the dopedphosphorus. Here, the sixth impurity region is also called p⁻ region.

In accordance with the processes set forth above, the impurity regionsthat have a conductivity type of n-type or p-type are formed in therespective semiconductor layers.

After forming the impurity regions, heat treatment, irradiation ofintense light, or irradiation of laser light is performed in order toactivate the impurity elements. In addition to the activation, it ispossible at the same time to recover plasma damage to the gateinsulating film and an interface between the gate insulating film andthe semiconductor layer. Particularly, excimer laser is used forirradiating from a side of a front surface or a rear surface in anatmosphere at a room temperature to 300° C. to activate the impurityelements. Besides, second harmonic of YAG laser may be irradiated forthe activation. YAG laser is a preferable means for activation sincelittle maintenance is necessary.

Next, a passivation film of an insulating film such as a siliconoxynitride film or a silicon oxide film is formed (not shown in thefigure). After that, a clean oven is used for heating at 300 to 550° C.for 1 to 12 hours to perform hydrogenation of the semiconductor films.In the present embodiment, heating at 410° C. for 1 hour is performed ina nitrogen atmosphere. In this process, it is possible to terminate adangling bond in the semiconductor film with hydrogen included in thepassivation film In addition to the hydrogenation, the above activationof the impurity element can also be performed at the same time.

After that, an interlayer insulating film 911 of an inorganic materialincluding silicon such as silicon oxide (SiO₂), silicon oxynitride(SiON), silicon oxynitride (SiNO), or silicon nitride (SiN) is formed onthe passivation film as shown in FIG. 10A. If a surface of theinterlayer insulating film has concavity and convexity formed at thistime, it is more preferable to perform planarization since bettercoverage is obtained in the processes of forming a light emitting layerand an electrode and characteristics of an element is likely to becomestable. For the planarization, etch back in which etching forplanarization is performed after forming a coating film such as s resistfilm, chemical mechanical polishing (CMP), or the like may be employed.In the present embodiment, a silicon oxide film is formed with plasmaCVD, and slurry appropriately selected from silica slurry, alumina(Al₂O₃) slurry with pH=3 to 4, or manganese oxide (MnO₂, Mn₂O₃) slurryis used to perform polishing with CMP for planarization.

Next, etching is performed sequentially to the passivation film, theinterlayer insulating film 911, and the gate insulating film 904 to forman opening portion (contact). For the etching at this time, dry etchingor wet etching may be employed. In the present embodiment, dry etchingis employed to form the opening portion. Then, after forming the openingportion, a metal film is formed on the interlayer insulating film 911and in the opening portion and etching of the metal film is performed toform source and drain electrodes 912, a source wiring, and a drainwiring as shown in FIG. 10B. As the metal film, a film of an element ofaluminum (Al), titanium (Ti), molybdenum (Mo), tungsten (W), or silicon(Si), or an alloy film including these elements may be used. In thepresent embodiment, after laminating a titanium film/a titanium-aluminumalloy film/a titanium film (Ti/Al-Ti/Ti), the drain electrode, thesource wiring, and the drain wiring are formed with patterning andetching performed for a desired shape.

After that, a material with a large work function is formed on a firstelectrode (a source electrode of a p-channel TFT in the pixel portion)to become an anode of a light emitting element to make injection of ahole easier in the light emitting element. As the material with thelarge work function, a translucent conductive material such as ITO(indium tin oxide) or IZO (indium zinc oxide), titanium nitride,zirconium nitride, or titanium carbide may be used. In addition,irradiation of ultraviolet light in an ozone atmosphere (Hereinafter, UVozone treatment) may be performed to further increase the work function.In the present embodiment, an ITO film with a large work function isformed in contact with the source wiring formed of the laminate film ofTi/Al-Ti/Ti.

Next, an insulator (also called a bank, a partition, or a barrier) 913for covering an end portion of the electrode 912 is formed as shown inFIG. 10C. For the insulator 913, photosensitive organic resin is used.For example, in the case of using negative photosensitive acrylic as amaterial of the insulator, the insulator 913 has a curved surface with afirst curvature radius at the top portion and a curved surface with asecond curvature radius at the bottom portion, and. it is preferable tomake the first and second curvature radiuses 0.2 μm to 3 μm. Inaddition, the insulator 913 may be covered with a protective film of analuminum nitride film, an aluminum oxynitride film, or a silicon nitridefilm. In the present embodiment, positive photosensitive acrylic is usedas a material of the insulator 913, which is further covered with aprotective film of an aluminum nitride film.

After that, a PVA (polyvinyl alcohol) porous body is used to wipe andremove a dust and the like. In the present embodiment, cleaning isperformed with bellclean to remove fme powder (dusts) produced inetching of the ITO and the insulating film.

Next, baking of PEDOT applied entirely may be performed as treatmentbefore evaporation of a light emitting layer. Since PEDOT dose not havea good wettability to ITO, it is preferable to perform washing withwater after applying PEDOT once and to apply PEDOT again. After that,heating is performed in an atmosphere under reduced pressure. In thepresent embodiment, heating is performed in an atmosphere under reducedpressure at 170° C. for 30 minutes and natural cooling is performed for30 minutes.

Next, an evaporation system is used to perform evaporation with anevaporation source in a deposition chamber subjected to vacuumevacuation to a degree of vacuum less than 5×10⁻³ Torr (0.665 Pa),preferably, 10⁻⁴ to 10⁻⁶ Pa. In the evaporation, an organic compound isevaporated with resistance heating in advance, and flies in alldirections when a shutter is opened at evaporation. The evaporatedorganic compound flies in an upward direction, and is evaporated to thesubstrate to form a light emitting layer (including a hole transportinglayer, a hole injecting layer, an electron transporting layer, anelectron injecting layer). The present embodiment has aromatic diamine(TPD) sealed in a first evaporation sources, p-EtTAZ sealed in a secondevaporation source, Alq₃ sealed in a third evaporation source, amaterial sealed in a fourth evaporation source in which a red lightemitting pigment of NileRed is added to Alq₃, and Alq₃ sealed in a fifthevaporation source, and deposition is performed with the materialssealed in the first to fifth evaporation sources to form a lightemitting layer 914 on the entire substrate as shown in FIG. 10D.

Next, a second electrode 915 is formed as a cathode on the lightemitting layer 914. A material that has a small work function and atranslucency to emitted light may be used for the second electrode 915,and low resistance is also desired for the material. In the presentembodiment, the second electrode 915 is formed of a laminate film of athin film including a metal (Li, Mg, or Cs) with a small work functionand a transparent conductive film (ITO: indium oxide-tin oxide alloy,In₂O₃-ZnO: indium oxide-zinc oxide alloy, or ZnO: zinc oxide) laminatedthereon. Further, an auxiliary electrode may be formed on the insulator913 in order to lower resistance of the cathode.

Although the light emitting layer 914 of low molecular weight materialswith evaporation, there is no limitation. A light emitting layer of apolymer material may be formed with coating such as spin coating orinkjet. Further, a layer of a polymer material and a layer of a lowmolecular weight material may be laminated.

After the above processes till forming the second electrode 915, anopposing substrate that has a sealing material formed may be bonded asexplained in Embodiment 2 in order to seal the light emitting elementformed over the substrate 901.

Embodiment 4

A semiconductor device according to the present invention has versatileapplications. In the present embodiment, a description will be given onexample of electronic apparatuses to which the present invention isapplicable.

As such electronic apparatuses, mobile information terminals such as anelectronic notebook, a mobile computer, a mobile phone, a video camera,a digital camera, a personal computer, and a television are given. Someexamples thereof are shown in FIGS. 11A to 11F.

FIG. 11A illustrates an EL display device which includes a casing 3301,a support table 3302, a display portion 3303, and the like. A displaydevice according to the present invention can be used for the displaydevice 3303.

FIG. 11B illustrates a video camera which includes a main body 3311, adisplay portion 3312, a sound input portion 3313, an operation key 3314,a battery 3315, an image receiving portion 3316, and the like. A displaydevice according to the present invention can be used for the displayportion 3312.

FIG. 11C illustrates a personal computer which includes a main body3321, a casing 3322, a display portion 3323, a keyboard 3324, and thelike. A display device according to the present invention can be usedfor the display portion 3323.

FIG. 11D illustrates a mobile information terminal which includes a mainbody 3331, a stylus pen 3332, a display portion 3333, an operation key3334, an external interface 3335, and the like. A display deviceaccording to the present invention can be used for the display portion3333.

FIG. 11E illustrates a mobile telephone which includes a main body 3401,a sound output portion 3402, a sound input portion 3403, a displayportion 3404, an operation key 3405, an antenna 3406, and the like. Adisplay device according to the present invention can be used for thedisplay portion 3404.

FIG. 11F illustrates a digital camera which includes a main body 3501, adisplay portion (A) 3502, a viewfinder 3503, an operation key 3504, adisplay portion (B) 3505, a battery 3506, and the like. A display deviceaccording to the present invention can be used for the display portion(A) 3502 and the display portion (B) 3505.

As set forth above, the present invention can be applied quite widely toelectronic apparatuses in various fields. The electronic apparatuses inthe present embodiment may employ any of configurations shown inEmbodiments 1 to 3.

In accordance with the present invention, a laminate film of a pluralityof different two or three coloring layers is used to form alight-shielding portion. As a result, a process for forming alight-shielding layer is reduced, which contributes to reduction ofmanufacturing cost and improvement of yield.

1. An electroluminescent display device comprising: a first substrate; afirst light emitting element supported by the first substrate; a secondlight emitting element supported by the first substrate; a secondsubstrate; a first coloring layer for filtering emitted light from thefirst light emitting element, supported by the second substrate andoverlapped with the first light emitting element; and a second coloringlayer for filtering emitted tight from the second light emittingelement, supported by the second substrate and overlapped with thesecond light emitting element, wherein the first substrate is oppositethe second substrate, and wherein a first portion between the first andsecond light emitting elements is overlapped with a second portion wherethe first coloring layer is overlapped with the second coloring layer.2. An electroluminescent display device according to claim 1, wherein alight emitting portion of a dummy pixel is overlapped with the secondportion.
 3. An electroluminescent display device according to claim 1,wherein a current monitoring pixel is overlapped with the secondportion.
 4. An electroluminescent display device according to claim 1,wherein the first and second coloring layers are covered with aplanarized protective film.
 5. An electroluminescent display deviceaccording to claim 1, wherein the electroluminescent display device is atop-emission type.
 6. An electroluminescent display device according toclaim 1, wherein the electroluminescent display device is an activematrix type.
 7. An electroluminescent display device comprising: a firstsubstrate; a first light emitting element supported by the firstsubstrate and including a first light emitting layer formed between afirst electrode and a second electrode; a second light emitting elementsupported by the first substrate and including a second light emittinglayer formed between a third electrode and a forth electrode; a secondsubstrate; a first coloring layer for filtering emitted light from thefirst light emitting element, supported by the second substrate andoverlapped with the first light emitting element; and a second coloringlayer for filtering emitted light from the second light emittingelement, supported by the second substrate and overlapped with thesecond light emitting element, wherein the first substrate is oppositethe second substrate, and wherein a first portion between the first andsecond light emitting elements is overlapped with a second portion wherethe first coloring layer is overlapped with the second coloring layer.8. An electroluminescent display device according to claim 7, wherein alight emitting portion of a dummy pixel is overlapped with the secondportion.
 9. An electroluminescent display device according to claim 7,wherein a current monitoring pixel is overlapped with the secondportion.
 10. An electroluminescent display device according to claim 7,wherein the first and second coloring layers are covered with aplanarized protective film.
 11. An electroluminescent display deviceaccording to claim 7, wherein each of end portions of the first andthird electrodes is covered by an insulator overlapped with the firstand second portions.
 12. An electroluminescent display device accordingto claim 7, wherein the first and second light emitting layers areconnected with each other.
 13. An electroluminescent display deviceaccording to claim 7, wherein the second and fourth electrodes areconnected with each other.
 14. An electroluminescent display deviceaccording to claim 7, wherein the electroluminescent display device is atop-emission type.
 15. An electroluminescent display device according toclaim 7, wherein the electroluminescent display device is an activematrix type.
 16. An electroluminescent display device comprising: afirst substrate; a thin film transistor supported by the firstsubstrate; an insulating film formed over the thin film transistor andsupported by the first substrate; a first light emitting element formedover the insulating film and supported by the first substrate; a secondlight emitting element formed over the insulating film and supported bythe first substrate; a second substrate; a first coloring layer forfiltering emitted light from the first light emitting element, supportedby the second substrate and overlapped with the first light emittingelement; and a second coloring layer for filtering emitted light fromthe second light emitting element, supported by the second substrate andoverlapped with the second light emitting element, wherein the firstsubstrate is opposite the second substrate, and wherein a first portionbetween the first and second light emitting elements is overlapped witha second portion where the first coloring layer is overlapped with thesecond coloring layer.
 17. An electroluminescent display deviceaccording to claim 16, wherein a light emitting portion of a dummy pixelis overlapped with the second portion.
 18. An electroluminescent displaydevice according to claim 16, wherein a current monitoring pixel isoverlapped with the second portion.
 19. An electroluminescent displaydevice according to claim 16, wherein the first and second coloringlayers are covered with a planarized protective film.
 20. Anelectroluminescent display device according to claim 16, wherein theinsulating film is planarized.
 21. An electroluminescent display deviceaccording to claim 16, wherein the electroluminescent display device isa top-emission type.
 22. An electroluminescent display device accordingto claim 16, wherein the electroluminescent display device is an activematrix type.
 23. An electroluminescent display device comprising: afirst substrate; a thin film transistor supported by the firstsubstrate; an insulating film formed over the thin film transistor andsupported by the first substrate; a first light emitting element formedover the insulating film, supported by the first substrate, andincluding a first light emitting layer formed between a first electrodeand a second electrode; a second light emitting element formed over theinsulating film, supported by the first substrate, and including asecond light emitting layer formed between a third electrode and a forthelectrode; a second substrate; a first coloring layer for filteringemitted light from the first light emitting element, supported by thesecond substrate and overlapped with the first light emitting element;and a second coloring layer for filtering emitted light from the secondlight emitting element, supported by the second substrate and overlappedwith the second light emitting element, wherein the first substrate isopposite the second substrate, and wherein a first portion between thefirst and second light emitting elements is overlapped with a secondportion where the first coloring layer is overlapped with the secondcoloring layer.
 24. An electroluminescent display device according toclaim 23, wherein a light emitting portion of a dummy pixel isoverlapped with the second portion.
 25. An electroluminescent displaydevice according to claim 23, wherein a current monitoring pixel isoverlapped with the second portion.
 26. An electroluminescent displaydevice according to claim 23, wherein the first and second coloringlayers are covered with a planarized protective film.
 27. Anelectroluminescent display device according to claim 23, wherein each ofend portions of the first and third electrodes is covered by aninsulator overlapped with overlapped with the first and second portions.28. An electroluminescent display device according to claim 23, whereinthe first and second light emitting layers are connected with eachother.
 29. An electroluminescent display device according to claim 23,wherein the second and fourth electrodes are connected with each other.30. An electroluminescent display device according to claim 23, whereinthe insulating film is planarized.
 31. An electroluminescent displaydevice according to claim 23, wherein the electroluminescent displaydevice is a top-emission type.
 32. An electroluminescent display deviceaccording to claim 23, wherein the electroluminescent display device isan active matrix type.
 33. An electroluminescent display devicecomprising: a first substrate; a first pixel having a first lightemitting element, supported by the first substrate; a second pixelhaving a second light emitting element, supported by the firstsubstrate; a dummy pixel having a third light emitting element,supported by the first substrate; a second substrate; a first coloringlayer for filtering emitted light from the first light emitting element,supported by the second substrate and overlapped with the first lightemitting element; and a second coloring layer for filtering emittedlight from the second light emitting element, supported by the secondsubstrate and overlapped with the second light emitting element, whereinthe first substrate is opposite the second substrate, wherein a firstportion between the first and second pixels is overlapped with a secondportion where the first coloring layer is overlapped with the secondcoloring layer, and wherein the dummy pixel is overlapped with a thirdportion where the first and second coloring layer is overlapped witheach other for shielding a light emitting portion of the dummy pixel.34. An electroluminescent display device according to claim 33, whereina current monitoring pixel is overlapped with the second portion.
 35. Anelectroluminescent display device according to claim 33, wherein thefirst and second coloring layers are covered with a planarizedprotective film.
 36. An electroluminescent display device according toclaim 33, wherein each of the first, second, and dummy pixels has a thinfilm transistor.
 37. An electroluminescent display device according toclaim 33, wherein the electroluminescent display device is atop-emission type.
 38. An electroluminescent display device according toclaim 33, wherein the electroluminescent display device is an activematrix type.